Hydrodynamic radial bearings are generally constructed with pads supported for pivotal motion about an axis parallel to the axis of rotation of the shaft being supported. The pivoting is generally provided by the flexing of the support structure for the bearing pad. The flexing occurs during rotation, as the fluid pressure builds at the bearing surface. In this manner, a wedge of fluid is formed between the bearing surfaces. A typical bearing of this construction is described in U.S. Pat. No. 5,513,917, which issued to Ide, the disclosure of which is incorporated herein by reference.
As described in the reference Ide, hydrodynamic bearings may be constructed by electric discharge machining (EDM) from a solid metal cylinder. These bearings have proven very effective at high speeds and are frequently used in turbines and other applications where high rotational speeds are reached. A problem arises as the size of the bearings increase to over three inches in diameter, as the replacement of such bearings becomes increasingly expensive. This is due to the unitary nature of hydrodynamic bearings constructed by EDM in which the pads, support and base are machined from a single element. In the larger bearings, there is, therefore, a need for a modular construction so that the individual parts may be repaired or replaced separately. It is a purpose of this invention to provide a modular bearing in which the bearing pad, the bearing support, and housing can be disassembled and repaired by the replacement of individual parts.
An additional problem which arises in the larger hydrodynamic bearings of a unitary type is their general inability to accommodate shaft misalignment or deflection. It is a purpose of this invention to construct a bearing support system that provides for additional pivotal motion about an axis transverse to the axis of rotation of the shaft being supported. This will allow the bearing pad to move in response to the stresses of misalignment.
A bearing is constructed of an assembly of three basic components, namely a bearing pad, an I beam shaped support element and a base. The I beam consists of inner and outer flanges connected by an intermediate web. The bearing pad is removably attached to the inner flange of the support element and the outer flange is removably attached to the base. Hydrodynamic bearing operation is provided by constructing the intermediate web so that it flexes about a linear pivot axis which is parallel to the axis of rotation of the supported shaft. In addition, the outer flanges are constructed to engage the base for pivotal motion about a linear axis which is transverse to the axis of rotation of the supported shaft. This is accomplished by constructing the outer mating surface of the outer flange with a second cylindrical curvature to allow a rocking movement on a stub shaft inserted at the interface of the outer flange and the base.